US 7,088,458 B1 · Apparatus and method for measuring an optical imaging system, and detector unit

Abstract

Apparatus and method for measuring an optical imaging system, and detector unit. The measuring apparatus contains an arrangement for combining wavefront and distortion measurements. For this purpose, respectively associated interferometry and Moiré structures can be introduced on the object side and image side. The detector unit contains a fiber plate and/or a flexible image conductor with a curved entry surface or with at least two different entry surfaces, which are offset axially or inclined spatially with respect to each other, or with an axially movable entry surface. By way of suitable wavefront acquisition in various lateral positions of object and/or image structure, a topographic calibration of the object or image structure can be carried out. Furthermore, by way of a Moiré technique, the lateral displacement travel in phase-shifting steps for the wavefront acquisition and, by way of point diffraction interferometry, the axial relative position of object and image structure can be determined highly accurately. The apparatus and method are used, in particular, for measuring lenses in microlithography installations.

Claims14

Dependent claims

An apparatus for measuring an optical imaging system, which comprises:

an arrangement for combined wavefront and distortion measurement, comprising
an object structure with an interferometry object structure for wavefront generation from illuminating light and a Moiré object structure for Moiré pattern generation, which are to be arranged simultaneously or alternatively on the object side, and
an image structure with an interferometry image structure matched to the interferometry object structure and a Moiré image structure matched to the Moiré object structure, which are to be arranged simultaneously or alternatively on the image side,
a spatially resolving detector unit which is arranged downstream of the image structure and has a first detector plane for the spatially resolving acquisition of interferometry wavefront information, and a second detector plane for the spatially resolving acquisition of Moiré image information for distortion measurement, or has an axially movable detector surface for the spatially resolving acquisition of interferometry wavefront information in a first axial position and for the spatially resolving acquisition of Moiré image information for distortion measurement in a second axial position.

1 more element

A method for measuring an optical imaging system, comprising:

performing a combined wavefront and distortion measurement, in which
an interferometry object structure for wavefront generation from illuminating light and a Moiré object structure for Moiré pattern generation are arranged simultaneously or alternatively on the object side,
an interferometry image structure matched to the interferometry object structure and a Moiré image structure matched to the Moiré object structure are arranged simultaneously or alternatively on the image side, and
using a first detector plane, interferometry wavefront information is acquired in a spatially resolving manner and, using a second detector plane, Moiré image information is acquired in a spatially resolving manner for distortion measurement, or the interferometry wavefront information and the Moiré image information for distortion measurement are acquired one after another in a spatially resolving manner with a detector surface which can be moved into two different axial positions.

1 more element

Dependencies are inferred from the claim text.

Apparatus and method for measuring an optical imaging system, and detector unit

Life of this patent

Apparatus and method for measuring an optical imaging system, and detector unit

Life of this patent

Abstract

Claims14